unload a code-created shape

Hi, I'm trying to get a detail image to load from xml, draw a line next to the picture based upon its dimensions, and repeat this process every time another thumbnail image is selected from the grid and loaded into the detail MovieClip. Everything is going great, save one tiny problem. The line draws in the correct place, but when I load the next image, the line from the previously loaded image is still there, along with the new one for the current image. The lines just accumulate. I tried removeChild-ing the MovieClip, but that makes it so the line stops loading at all. Is there a way to clear the dimensions of all current graphics properties in the lineDrawing MovieClip either as the old image is unloaded or the new one is loaded? Here's my code, thanks for any help!